The present invention relates generally to the field of printing and is more particularly concerned with apparatus for printing indicia on objects including food products, fruits and the like, and wherein the indicia may be selectively and interchangeably applied by inks having different characteristics.
A number of printing machines have been developed for applying ink indicia such as trademarks, trade names, designs and the like upon large numbers of objects such as those set forth above in a continuous, high speed operation. A typical printing machine of this type is disclosed by U.S. Pat. No. 2,987,991 issued June 13, 1961 to M. V. Johnson, Jr., et al and assigned to the assignee of the present invention, and is incorporated by reference into the present application.
Printing machines such as disclosed in the above patent include a continuous conveyor carrying a plurality of specially shaped and spaced apart rotatable rollers capable of orienting and aligning objects such as fruits and vegetables. In particular, the conveyor is adapted to orient ellipsoidally shaped articles or objects so that the long or major axes of the objects are parallel to the axes of the rollers. The conveyor then carries the fruits or objects successively to a printing station where inked printing dies apply an ink indicia upon the fruit or objects which are then transferred to a suitable receiver or for further processing.
Machines of this type have been highly developed in order to assure continued high speed operation over extended periods of time. For example, the machines are equipped with special ink rolls providing a sufficient ink supply for long periods of operation. To prevent damage to the fruits or other objects, the printing machines are equipped with die rolls including flexible mounting means for supporting the printing dies which transfer ink from the ink roll to the fruit or other objects as they are moved past the printing roll.
Machines of this type have been found generally to be satisfactory for the printing of indicia upon such objects. However, it has been discovered that it is often necessary and desirable to use inks or marking materials which vary widely as to the characteristics. For example, different citrus fruits such as lemons and oranges are typically stamped with indicia in different colors of ink to increase visibility of the mark. It may even be necessary or desirable at times to employ different inks upon the same type of fruit.
In the past, this has necessitated disassembly of the printing machine in order to replace the ink roll with another ink roll carrying the particular ink that is to be used. Such procedures result in undesirable delays and interfere with high speed processing of the fruits or other objects and thus cause inefficiency in the processing operations. Accordingly, a great need arises for a printing apparatus in which inks or marking materials of differing characteristics may be rapidly selected and interchanged without substantially interrupting or interfering with operation of the printing machine.